This invention relates to warning systems for vehicles to advise the operator of road icing conditions that may exist, and more particularly to a warning system which uses an infrared detector to determine the temperature specifically of the road surface itself, to advise of road conditions which promote the formation of hazardous ice conditions including black ice on roadways.
Ice warning systems heretofore known in the art have involved the use of basic temperature sensors arranged to inform the operator of a vehicle of the ambient temperature, so that the operator will know when freezing air temperatures are occurring. However, because of so many variables, such as winds, heat stored in the earth, differing road surfaces, road heating from vehicle traffic, etc., air temperature is a very unreliable indicator of actual icing conditions existing on roadway surfaces. Black ice may exist in air temperatures above 32.degree. F. (0.degree. C.), and conversely, wet road conditions may be present at air temperatures below freezing. Moreover, the strikingly different road surface conditions may even alternate from one to the other along a road despite the air temperature remaining relatively constant as the vehicle travels.
Thus, a reliance on air temperature not only does not give an accurate indication of actual driving conditions, it can, and in fact often does give one a dangerously false sense of security in the existing road conditions.
No system heretofore has been available which is arranged specifically to read the temperature of the road surface itself, as a vehicle is traveling, to give an accurate accounting of the condition of the road surface irrespective of the air temperature in the surrounding vicinity.